Highly diverse composite materials are used in the field of the construction and equipping of buildings in general, in particular residential buildings or offices and public buildings (museums, cinemas, concert halls, and the like). Some of these materials, such as acoustic and/or thermal insulators, wood panels, furniture units or decorative items, use adhesives, paints and varnishes which comprise formaldehyde-based resins.
These resins are highly advantageous as they are inexpensive and have excellent performances. Their major disadvantage lies in the fact that they comprise free formaldehyde and consequently that they are capable of emitting formaldehyde over time.
In recent years, the proportion of formaldehyde in resins has greatly decreased due to the application of stricter regulations with regard to protection from undesirable emissions of volatile organic products which may exhibit a risk to the health of individuals. However, the attempts which have consisted in replacing the abovementioned resins with other formaldehyde-free resins have not been successful due to the very much higher cost and the poorer quality of the products obtained.
Nevertheless, it is still desirable for the content of formaldehyde in the ambient air of buildings for residential use to be as low as possible.
Means are known for achieving this aim.
The proposal has been made to include particles of photocatalytic titanium oxide in a paint or a plaster material (US-A-2005/0226761) or in paper or a textile, plastic or wooden material (EP-A-1 437 397).
JP-A-11128329 describes the use of an ammonium salt in an interior building material, such as a plasterboard.
JP-A-2002145655 provides for the inclusion of urea and/or melamine in a plasterboard.
JP-A-10337803 describes the incorporation of a hydrazine derivative in a plasterboard. The proposal is also made to include at least one hydrazide in combination a) with an inorganic absorbent in a plasterboard or in a decorative layer on wood (JP-A-2000103002), b) with silica gel in a plasterboard (JP-A-2004115340) or c) with an organic carbide (US-A-20040101695) in an interior building material.